Re: [lmi] Failed vim-mode .zshrc experiment

[Vadim Zeitlin]

On Fri, 25 Oct 2019 18:21:28 +0000 Greg Chicares <address@hidden> wrote:

GC> but that can't work because $KEYMAP is internal to ZLE. But that's
GC> not what you recommended--you propose defining $PS1 globally, and
GC> then using the functions to modify it. Here's how I've experimentally
GC> implemented that:
GC> 
GC> prompt='%d[%?]%(!.#.$)'
GC> 
GC> function zle-line-init zle-keymap-select {
GC>     if [[ ${KEYMAP} == vicmd ]]; then
GC>         prompt="%F{yellow}${prompt}%f"
GC>     else
GC>         prompt="${${prompt##%F{yellow\}}%%%f}"
GC>     fi
GC>     zle reset-prompt
GC> }
GC> 
GC> zle -N zle-line-init
GC> zle -N zle-keymap-select
GC> 
GC> IMO that's drastically worse.

 It's less clear as written, but when you change your PS1 in your .zshrc in
a couple of years (or however long it will take you to forget everything
about changing it in ZLE functions -- it could be a couple of days for me)
you won't have to spend an hour trying to understand why does the new value
get lost.

GC> I arrived at that through experimentation, but one minute later I can't
GC> understand it.

 That's fine, nobody understands shell code. It just works.

GC> And even if this were comprehensible and maintainable, it still seems
GC> fragile. What does the prompt become if we paste the following line
GC> into the terminal?
GC>   prompt="abc%F{red}%F{yellow}%f%fxyz$"
GC> 
GC> Did you have a cleaner implementation in mind?

 I thought to just save the original value of the prompt in a global
variable, i.e.

        if [[ ${KEYMAP} == vicmd ]]; then
                VZ_SAVED_PROMPT=$prompt
                prompt="%F{yellow}${prompt}%f"
        else
                if [[ -n $VZ_SAVED_PROMPT ]]; then
                        prompt=$VZ_SAVED_PROMPT
                fi
        fi

I haven't actually tested it, but thinking about it more, this approach
does have at least one problem: if you change the prompt interactively, it
will be overwritten by the saved prompt. But this could be solved by
replacing the test for the saved prompt being non-empty with comparison of
the current prompt with "%F{yellow}${VZ_SAVED_PROMPT}%f", at the price of
some minor extra complexity.


 Alternatively, I think your implementation could be made a bit clearer by
using sed (shell substitutions are so bad that even sed is clearer than
them!) as

        sed -e 's/^%F{yellow}\(.*\)%f$/\1/'

doesn't seem too bad. But I wouldn't want to launch an extra program for
each prompt display just to avoid the (perfectly unreadable, but, again,
who is going to read them anyhow) shell substitutions above.


GC> But doesn't vim's "normal mode" correspond to zsh's vicmd mode,

 Sorry, I inadvertently used very confusing terminology, I should have said
"main keymap" instead. You did understand what I was trying to say
eventually, sorry for making this task needlessly difficult.

 Regards,
VZ

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